Generally, a cooking apparatus is represented by products such as a conventional heat oven and a microwave oven. The microwave oven is a type of cooking apparatus used to cook food using only a magnetron or jointly a magnetron and a heater, and the oven is another type of cooking apparatus used to cook food by heating using dry heat hermetically sealed food. Here, electricity or gaseous fuel is used as a heat source.
The cooking apparatus is further represented by, for example, a frying pan and a pot, which have a surface directly contacting food.
The conventional heat oven and/or the microwave oven includes an oven body forming the external appearance thereof, a cooking chamber defining a space for receiving food, a door for opening and closing the cooking chamber, and a heating unit for heating the food in the cooking chamber.
The cooking chamber is a cooking space defined in the oven body. The door is hingedly coupled to the front of the oven body such that the door is opened and closed in the vertical direction and/or in the lateral direction. The heating unit is mounted in the cooking chamber at one side thereof for supplying thermal energy necessary to cook the food. The thermal energy, generated from the heating unit, is transmitted to the food by convection or radiation.
However, the above-described conventional cooking apparatus has the following problems.
First, the conventional cooking apparatus has a problem in that the surface of the cooking apparatus, exposed to the food, does not simultaneously satisfy heat resistance, durability, and cleanability. In the conventional cooking apparatus, enamel is generally used for improving abrasion resistance and heat resistance at the region exposed to the food. However, the food easily sticks to the cooking chamber when the enamel is used to construct the cooking chamber.
Also, Teflon, exhibiting excellent cleanability, may be used to prevent the food from sticking to the cooking chamber. However, Teflon does not satisfy the heat resistance and the abrasion resistance.
Second, when contaminants, such as oil, generated during the cooking of the food, sticks to the inner wall of the cooking chamber, the heating unit is operated at a high temperature, for example at 450° C. or more, for two hours or more to burn the contaminants which are stuck to the inner wall of the cooking chamber. With such an operation, the contaminants are removed from the inner wall of the cooking chamber.
When the interior of the cooking chamber is maintained at such a high temperature for a long period of time, however, the power consumed by the heating unit is greatly increased, and a user is restricted for a period of time from using the cooking apparatus.
Third, the cooking apparatus, such as the conventional oven and/or the microwave oven, has a high-temperature cleaning function to burn the contaminants. Due to the high-temperature cleaning function, however, the temperature of a door glass located at the front of the cooking chamber also increases. The door glass is directly exposed to the user, with the result that the user may suffer a burn by the high-temperature door glass.
Lastly, the higher the internal temperature of the cooking chamber is, the thicker an insulation member for isolating thermal energy leaking from the cooking chamber is. When the thickness of the insulation member is increased, the manufacturing costs of the product are increased as well, and, in addition, the space of the cooking chamber becomes relatively smaller.